Theresa May proposed pausing a full Brexit until 2021 by asking EU countries to agree to a two-year transition period during which the UK would continue to enjoy unfettered access to the single market.

Britain needs “political adults” to work together to halt a damaging Brexit, Vince Cable will tell the Liberal Democrat conference on Tuesday, urging moderate Conservatives and Labour MPs to work with his party.

Boris Johnson has insisted that Britain will still claw back £350m a week after leaving the EU, with much of that money preferably being spent on the NHS, as he warned critics of Brexit against treating 17.4 million voters as fools.

A Norway-style arrangement would give post-Brexit Britain access to the single market and would not lead to fights with the European court of justice, the head of the court that oversees single market countries outside the EU has claimed.